About a hundred million years ago, the sea retreated and tectonic plate movement created a fault-line at Corconne. The Oligocene period followed, with the formation of the Pyrenees and the fold of the Pic St. Loup. Then the Quaternary, from minus 1.6 million years up to the present – a series of glaciations. During the cold periods, the limestone cliffs were carved out of the plateau. With the melting of the glaciers of the Massif Central, running water swept the surface of the plateau depositing piles of pebbles at the base of the cliffs. So was made this stony soil, poor and deep (easily 5 metres). The roots can establish themselves at depth without encountering any barriers, assuring a regular, but not excessive, supply of water.